*{padding:0;margin:0}
html,body {
    height: 100%;
    background-color: #000;
}
.total {
        width: 300px;
        height: 30px;
        border: solid purple 5px;
        position: relative;
        top: 0;
        left: 0;
        z-index: 2;
        display: none;
    }

.total .num {
        position: absolute;
        top: 0;
        left: 0;
        height: 30px;
        background-color: red;
    }

#btn {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    margin: auto;
    width: 100px;
    height: 50px;
    background-color: skyblue;
    color: rgb(247, 37, 201);
    font-size: larger;
}